JPH11313356A - Mobile communication system - Google Patents
Mobile communication systemInfo
- Publication number
- JPH11313356A JPH11313356A JP11750798A JP11750798A JPH11313356A JP H11313356 A JPH11313356 A JP H11313356A JP 11750798 A JP11750798 A JP 11750798A JP 11750798 A JP11750798 A JP 11750798A JP H11313356 A JPH11313356 A JP H11313356A
- Authority
- JP
- Japan
- Prior art keywords
- control signal
- base station
- mobile station
- signal
- mobile
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
- 238000010295 mobile communication Methods 0.000 title claims abstract description 39
- 230000005540 biological transmission Effects 0.000 claims abstract description 86
- 238000004891 communication Methods 0.000 claims description 39
- 238000012544 monitoring process Methods 0.000 claims 6
- 238000000034 method Methods 0.000 description 26
- 238000010586 diagram Methods 0.000 description 13
- 230000001413 cellular effect Effects 0.000 description 8
- 230000001771 impaired effect Effects 0.000 description 1
- 230000002452 interceptive effect Effects 0.000 description 1
- 238000000926 separation method Methods 0.000 description 1
- 230000007704 transition Effects 0.000 description 1
Classifications
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04W—WIRELESS COMMUNICATION NETWORKS
- H04W36/00—Hand-off or reselection arrangements
- H04W36/16—Performing reselection for specific purposes
- H04W36/18—Performing reselection for specific purposes for allowing seamless reselection, e.g. soft reselection
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04W—WIRELESS COMMUNICATION NETWORKS
- H04W36/00—Hand-off or reselection arrangements
- H04W36/24—Reselection being triggered by specific parameters
- H04W36/30—Reselection being triggered by specific parameters by measured or perceived connection quality data
- H04W36/302—Reselection being triggered by specific parameters by measured or perceived connection quality data due to low signal strength
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04W—WIRELESS COMMUNICATION NETWORKS
- H04W52/00—Power management, e.g. TPC [Transmission Power Control], power saving or power classes
- H04W52/04—TPC
- H04W52/38—TPC being performed in particular situations
- H04W52/40—TPC being performed in particular situations during macro-diversity or soft handoff
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04W—WIRELESS COMMUNICATION NETWORKS
- H04W52/00—Power management, e.g. TPC [Transmission Power Control], power saving or power classes
- H04W52/04—TPC
- H04W52/06—TPC algorithms
- H04W52/14—Separate analysis of uplink or downlink
- H04W52/146—Uplink power control
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04W—WIRELESS COMMUNICATION NETWORKS
- H04W52/00—Power management, e.g. TPC [Transmission Power Control], power saving or power classes
- H04W52/04—TPC
- H04W52/18—TPC being performed according to specific parameters
- H04W52/24—TPC being performed according to specific parameters using SIR [Signal to Interference Ratio] or other wireless path parameters
Landscapes
- Engineering & Computer Science (AREA)
- Computer Networks & Wireless Communication (AREA)
- Signal Processing (AREA)
- Mobile Radio Communication Systems (AREA)
Abstract
Description
【０００１】[0001]
【発明の属する技術分野】本発明は、ＣＤＭＡ（Code D
ivision Multiple Access）方式で基地局と移動局とが
接続されてなるセルラー方式の移動通信システムに関
し、詳しくは、移動局がセル間を移動するときに下りリ
ンク伝送信号についてソフトハンドオフを行う移動通信
システムに関する。The present invention relates to a CDMA (Code D)
The present invention relates to a cellular mobile communication system in which a base station and a mobile station are connected by an ivision multiple access (ivision multiple access) system, and more particularly, to a mobile communication system that performs soft handoff on a downlink transmission signal when the mobile station moves between cells. About.
【０００２】[0002]
【従来の技術】直接拡散ＣＤＭＡ方式のセルラーシステ
ムにおいては、上りリンク伝送信号の通信容量を最大化
するために、遠近問題を避けるべく移動局の送信電力制
御を行うのが一般的である。そのために、下りチャンネ
ルにおいて基地局は、各移動局に対して送信電力制御信
号を送信する。一方、直接拡散ＣＤＭＡ方式のセルラー
システムにおいて、通常、基地局及び移動局は、複数の
復調器を有し、マルチパス成分の分離や、ソフトハンド
オフ処理を行うようになされている。2. Description of the Related Art In a direct spread CDMA cellular system, in order to maximize the communication capacity of an uplink transmission signal, transmission power control of a mobile station is generally performed to avoid a near-far problem. For this purpose, the base station transmits a transmission power control signal to each mobile station in the downlink channel. On the other hand, in a direct spread CDMA cellular system, a base station and a mobile station usually have a plurality of demodulators to perform multipath component separation and soft handoff processing.
【０００３】このソフトハンドオフ処理は、図５に示す
ように、各セル１０１，１０２間を移動局１０３が移動
して一方のセル１０１及び他方のセル１０２の重複部分
１０４に移動局１０３が位置すると、移動局１０３が基
地局１０５ａから受信する信号品質の劣化が生ずる。こ
のとき、移動局１０３に対し複数の基地局１０５ａと基
地局１０５ｂからほぼ同じ信号が送信され、移動局１０
３はこの信号をそれぞれ復調して合成することにより、
信号品質の改善を図っている。また、上りリンクに関し
ても、移動局１０３から送信された信号は複数の基地局
１０５ａ及び基地局１０５ｂによって復調されるととも
に合成され、信号品質の改善が図られている。In this soft handoff process, as shown in FIG. 5, when the mobile station 103 moves between the cells 101 and 102 and the mobile station 103 is located in the overlapping portion 104 of one cell 101 and the other cell 102, Then, the quality of the signal received by the mobile station 103 from the base station 105a is degraded. At this time, substantially the same signal is transmitted from the plurality of base stations 105a and 105b to the mobile station 103, and the mobile station 10
3 demodulates and combines these signals,
Improves signal quality. Also, regarding the uplink, the signal transmitted from the mobile station 103 is demodulated and synthesized by the plurality of base stations 105a and 105b, thereby improving the signal quality.
【０００４】このとき、各基地局１０５ａと基地局１０
５ｂからの送信電力制御信号は、各基地局１０５ａ，１
０５ｂにおいて独立して生成される。このことは、移動
局１０３に一方の基地局１０５ａからのみ送信電力制御
信号が送信されているとき、移動局１０３で上述の処理
を行い基地局１０５ａにおいて最適なレベルで受信でき
るように送信電力を制御して移動局１０３が送信を行う
と、他方の基地局１０５ｂにとっては予期しない信号と
なり大きな妨害となる虞があることによる。そして、移
動局１０３は、複数の基地局１０５ａ，１０５ｂからの
送信電力制御信号を独立して復調し、これらの信号を合
成している。具体的には、移動局１０３は、例えば双方
の基地局１０５ａ，１０５ｂから送信電力制御信号が
「ｕｐ」を示すときにのみ送信電力を大きくし、基地局
１０５ａ又は基地局１０５ｂのうち少なくとも一の基地
局からの送信電力制御信号が「ｄｏｗｎ」を示すときに
は送信電力を減少させる。このように、移動局１０３
は、各基地局１０５ａ，１０５ｂからの送信電力信号を
独立して受信・復調することで、各基地局１０５ａ，１
０５ｂに適切な送信電力で上りリンク信号を送信する。At this time, each base station 105a and base station 10
5b is transmitted from each base station 105a, 1
Independently generated at 05b. This means that when the transmission power control signal is transmitted to the mobile station 103 from only one base station 105a, the mobile station 103 performs the above-described processing and reduces the transmission power so that the base station 105a can receive the signal at an optimal level. When the mobile station 103 performs transmission under control, an unexpected signal is generated for the other base station 105b, which may cause a great interference. Then, the mobile station 103 independently demodulates the transmission power control signals from the plurality of base stations 105a and 105b, and combines these signals. Specifically, for example, the mobile station 103 increases the transmission power only when the transmission power control signal from both base stations 105a and 105b indicates “up”, and at least one of the base station 105a and the base station 105b. When the transmission power control signal from the base station indicates “down”, the transmission power is reduced. Thus, the mobile station 103
Respectively receives and demodulates the transmission power signals from the base stations 105a and 105b independently, so that the base stations 105a and 105b
An uplink signal is transmitted with appropriate transmission power at 05b.
【０００５】[0005]
【発明が解決しようとする課題】上述のように、直接拡
散ＣＤＭＡ方式を採用したセルラーシステムにおいて
は、移動局の送信電力制御が必須の技術となる。また、
このセルラーシステムにおいては、システム全体での通
信容量を最大とするために、干渉を最小限に抑制する必
要がある。このため、セルラーシステムにおいて、ソフ
トハンドオフ処理を行っている。このソフトハンドオフ
時、移動局１０３は、複数の基地局１０５ａ，１０５ｂ
からの異なる送信電力制御信号を復調して合成すること
で送信電力制御を行わなければならない。As described above, in a cellular system employing a direct spread CDMA system, transmission power control of a mobile station is an essential technique. Also,
In this cellular system, it is necessary to minimize interference in order to maximize the communication capacity of the entire system. For this reason, soft handoff processing is performed in the cellular system. At the time of this soft handoff, the mobile station 103 establishes a plurality of base stations 105a and 105b.
The transmission power control must be performed by demodulating and combining different transmission power control signals from.
【０００６】このとき、ソフトハンドオフを開始する通
信品質についての閾値を低く設定すると、複数チャンネ
ル分の通信資源を使用するソフトハンドオフを行わなけ
ればならない移動局数が増加し、システム全体の通信容
量が減少してしまうという問題があった。At this time, if the threshold value for the communication quality at which the soft handoff is started is set low, the number of mobile stations that must perform the soft handoff using the communication resources for a plurality of channels increases, and the communication capacity of the entire system is reduced. There was a problem that it would decrease.
【０００７】逆に、ソフトハンドオフを開始する通信品
質の閾値を高く設定すると、ハンドオフがなされる領域
に移動局１０３が存在する確率が減るためにソフトハン
ドオフの頻度が少なくなりシステムの通信容量は大きく
できそうではあるが、隣接する基地局１０５ｂへの通信
信号を妨害する可能性が大きくなってしまい、干渉のた
めそのシステム全体の容量が少なくなるばかりかシステ
ム全体の安定性が損なわれるという問題を有している。On the contrary, if the communication quality threshold value for starting soft handoff is set high, the probability of the mobile station 103 being present in the area where handoff is performed is reduced, so that the frequency of soft handoff is reduced and the communication capacity of the system is increased. Although it is possible, the possibility of interfering with the communication signal to the adjacent base station 105b increases, and the problem that not only the capacity of the whole system is reduced due to the interference but also the stability of the whole system is impaired is reduced. Have.
【０００８】また、ハンドオフがなされる領域に移動局
１０３が位置するときにおいてハンドオフ先の基地局１
０５ｂの通信容量が許容値に達しているときには、ソフ
トハンドオフは行われず、周波数チャンネルを変更する
ハードハンドオフを行うことになる。このとき、移動局
１０３からハードハンドオフを行う前の周波数チャンネ
ルで通信信号が上りリンクで送信されると、基地局１０
５ｂが扱っている通信信号に対して予期しない大きな妨
害を与え、他局の通信を妨害してしまう問題があった。When the mobile station 103 is located in the area where the handoff is to be performed, the handoff destination base station 1
When the communication capacity 05b has reached the allowable value, soft handoff is not performed, and hard handoff for changing the frequency channel is performed. At this time, if a communication signal is transmitted in uplink from the mobile station 103 on the frequency channel before performing the hard handoff, the base station 10
There is a problem that unexpected large interference is caused to the communication signal handled by 5b, and communication of other stations is interrupted.
【０００９】そこで、本発明は、上述したような実情に
鑑みて提案されたものであり、ソフトハンドオフを行い
ながら、システム全体の容量を大きくするとともに移動
局送信電力の制御を正しく行ってシステム全体の安全性
を保持する移動通信システムを提供することを目的とす
る。Accordingly, the present invention has been proposed in view of the above-described circumstances, and it has been proposed to increase the capacity of the entire system while performing soft handoff and to properly control the transmission power of the mobile station. It is an object of the present invention to provide a mobile communication system that maintains the security of the mobile communication system.
【００１０】[0010]
【課題を解決するための手段】上述の課題を解決する本
発明に係る移動通信システムは、複数の基地局と、各基
地局により形成されるセル間を移動する移動局とが符号
分割多元接続方式で接続され、上記基地局による送信電
力制御命令に従って移動局の送信電力制御がなされる移
動通信システムにおいて、少なくとも下りリンク制御信
号について上記移動局と上記各基地局とを同時に接続す
るソフトハンドオフ制御を行い、上記下りリンク制御信
号以外の下りリンク信号についてはハードハンドオフ制
御を行うことを特徴とするものである。A mobile communication system according to the present invention for solving the above-mentioned problems comprises a plurality of base stations and a mobile station moving between cells formed by the respective base stations. Handoff control for simultaneously connecting the mobile station and each of the base stations with respect to at least a downlink control signal in a mobile communication system in which transmission power control of the mobile station is performed according to a transmission power control command from the base station. And performing hard handoff control for downlink signals other than the downlink control signal.
【００１１】このような移動通信システムによれば、少
なくとも下りリンク制御信号についてソフトハンドオフ
制御を行うので、システムの通信容量を増加させ、シス
テムの安定性を保持する。According to such a mobile communication system, soft handoff control is performed on at least the downlink control signal, so that the communication capacity of the system is increased and the stability of the system is maintained.
【００１２】[0012]
【発明の実施の形態】以下、本発明の実施の形態につい
て図面を参照しながら詳細に説明する。Embodiments of the present invention will be described below in detail with reference to the drawings.
【００１３】図１は、本実施の形態に係る移動体通信シ
ステム１を示す図である。この移動体通信システム１は
複数の基地局２（２ａ，２ｂ）と、複数の移動局３とか
らなり、直接拡散ＣＤＭＡ（Code Division Multiple A
ccess）方式で基地局２と移動局３とが接続されてなる
セルラーシステムであるが、本実施の形態では、説明の
便宜のため、第１の基地局２ａと、移動局３と、第２の
基地局２ｂとの関係のみについて説明する。FIG. 1 is a diagram showing a mobile communication system 1 according to the present embodiment. This mobile communication system 1 is composed of a plurality of base stations 2 (2a, 2b) and a plurality of mobile stations 3, and is directly spread CDMA (Code Division Multiple A).
ccess) system is a cellular system in which the base station 2 and the mobile station 3 are connected. In the present embodiment, for convenience of explanation, the first base station 2a, the mobile station 3, and the second Only the relationship with the base station 2b will be described.
【００１４】第１の基地局２ａは、図１に示すように第
１の領域４内に移動局３が位置するとき、当該移動局３
と上りリンク信号及び下りリンク信号の送受信を行う。
第１の基地局２ａは、移動局３の送信電力制御信号等の
制御信号と音声データ等の情報信号とからなる下りリン
ク信号を移動局３に送信する。When the mobile station 3 is located in the first area 4 as shown in FIG. 1, the first base station 2a
And transmit and receive uplink signals and downlink signals.
The first base station 2a transmits to the mobile station 3 a downlink signal including a control signal such as a transmission power control signal of the mobile station 3 and an information signal such as voice data.
【００１５】第２の基地局２ｂは、上述の第１の基地局
２ａと同様に、移動局３が第２の領域５内に位置すると
き、当該移動局３と上りリンク信号及び下りリンク信号
の送受信を行う。When the mobile station 3 is located in the second area 5, the second base station 2b communicates with the mobile station 3 in the same manner as the first base station 2a. Transmission and reception.
【００１６】送信電力制御信号は、移動局３が適切なレ
ベルで上りリンク信号を第１の基地局２ａ或いは第２の
基地局２ｂに送信するように、上りリンク信号の送信電
力レベルを適応的に変化させる信号である。The transmission power control signal adaptively adjusts the transmission power level of the uplink signal so that the mobile station 3 transmits the uplink signal at an appropriate level to the first base station 2a or the second base station 2b. This is a signal that changes to
【００１７】移動局３は、図１（ａ）に示すように、第
１の領域４内に位置するときには、第１の基地局２ａか
らの下りリンク信号を受信するとともに第１の基地局２
ａに上りリンク信号を送信する。このとき、移動局３の
受信電力は、図２中の領域Ａに示すように、第１の基地
局２ａからの下りリンク信号の受信電力が閾値ａ以上で
あり、第２の基地局２ｂからの下りリンク信号が閾値ｂ
以下である。したがって、移動局３は、第１の基地局２
ａからの下りリンク信号のみを受信するとともに復調す
ることとなる。As shown in FIG. 1A, when the mobile station 3 is located in the first area 4, the mobile station 3 receives the downlink signal from the first base station 2a and receives the downlink signal from the first base station 2a.
a to transmit an uplink signal. At this time, as shown in the area A in FIG. 2, the reception power of the mobile station 3 is such that the reception power of the downlink signal from the first base station 2a is equal to or higher than the threshold a and the second base station 2b The downlink signal of the threshold b
It is as follows. Therefore, the mobile station 3 is connected to the first base station 2
Only the downlink signal from a is received and demodulated.
【００１８】また、移動局３は、図１（ｂ）に示すよう
に、第１の領域４から第２の領域５に向かって移動し、
第１の領域４と第２の領域５との重複領域６に位置する
ときには、ハンドオフ状態となされ、第１の基地局２ａ
及び第２の基地局２ｂから下りリンク信号が送信される
ソフトハンドオフ状態となされる。このとき、移動局３
の受信電力は、図２中の領域Ｂに示すように、時刻ｔ１
において第２の基地局２ｂからの受信電力が閾値ｂに達
する。そして、移動局３は、第１の基地局２ａ及び第２
の基地局２ｂの双方から下りリンク信号を受信する。さ
らに移動局３が第１の基地局２ａから第２の基地局２ｂ
の方向に移動すると、第１の基地局２ａからの下りリン
ク信号の受信電力よりも第２の基地局２ｂからの下りリ
ンク信号の受信電力が大きくなり、時刻ｔ２において第
１の基地局２ａからの受信電力が閾値ａに達する。そし
て、移動局３は、第１の基地局２ａからの下りリンク信
号を受信せず、第２の基地局２ｂからの下りリンク信号
を受信する。すなわち、この時刻ｔ１から時刻ｔ２に達
する領域Ｂでは、移動局３が第１の基地局２ａ及び第２
の基地局２ｂの双方の下りリンク信号を受信するととも
に復調するソフトハンドオフ状態とされる。The mobile station 3 moves from the first area 4 to the second area 5 as shown in FIG.
When located in the overlapping area 6 of the first area 4 and the second area 5, a handoff state is established and the first base station 2a
And a soft handoff state in which a downlink signal is transmitted from the second base station 2b. At this time, mobile station 3
At the time t1 as shown in the area B in FIG.
, The reception power from the second base station 2b reaches the threshold value b. Then, the mobile station 3 includes the first base station 2a and the second base station 2a.
Downlink signal is received from both of the base stations 2b. Further, the mobile station 3 moves from the first base station 2a to the second base station 2b.
, The received power of the downlink signal from the second base station 2b becomes larger than the received power of the downlink signal from the first base station 2a, and at time t2 from the first base station 2a. Reaches the threshold a. Then, the mobile station 3 does not receive the downlink signal from the first base station 2a, but receives the downlink signal from the second base station 2b. That is, in the area B from the time t1 to the time t2, the mobile station 3 is connected to the first base station 2a and the second base station 2a.
The base station 2b enters a soft handoff state in which both downlink signals are received and demodulated.
【００１９】さらに、移動局３は、図１（ｃ）に示すよ
うに、重複領域６から移動して第２の領域５内に位置す
るときには、第２の基地局２ｂからの下りリンク信号を
受信するとともに第２の基地局２ｂに上りリンク信号を
送信する。このとき、上述したように、移動局３の受信
電力は、移動局３が第１の基地局２ａから第２の基地局
２ｂに向かって移動することで、図２中の領域Ｃに示す
ように、第２の基地局２ｂからの下りリンク信号の受信
電力が閾値ｂ以上となり、第１の基地局２ａからの下り
リンク信号の受信電力が閾値ａ以下となっている。した
がって、移動局３は、第２の基地局２ｂからの下りリン
ク信号のみを受信するとともに復調することとなる。Further, as shown in FIG. 1C, when the mobile station 3 moves from the overlapping area 6 and is located in the second area 5, the mobile station 3 transmits the downlink signal from the second base station 2b. It receives and transmits an uplink signal to the second base station 2b. At this time, as described above, the received power of the mobile station 3 is increased as shown in the area C in FIG. 2 by the mobile station 3 moving from the first base station 2a to the second base station 2b. In addition, the reception power of the downlink signal from the second base station 2b is equal to or higher than the threshold b, and the reception power of the downlink signal from the first base station 2a is equal to or lower than the threshold a. Therefore, the mobile station 3 receives and demodulates only the downlink signal from the second base station 2b.
【００２０】なお、この移動体通信システム１において
は、移動局３が第１の領域４から重複領域６に移動した
とき、移動局３側からハンドオフ処理に入る指示を出す
方式（Mobile Assisted Hand Off:MAHO）を採用しても
良く、さらには基地局２側からハンドオフ状態に入る指
示を出す方式を採用しても良く、第１の基地局２ａ及び
第２の基地局２ｂと接続されている通常の状態からハン
ドオフ状態への移行の過程は任意の方式でよい。また、
この移動体通信システム１においては、ハンドオフ状態
から通常の状態に移行する過程も任意の方式でよい。In the mobile communication system 1, when the mobile station 3 moves from the first area 4 to the overlapping area 6, a method for issuing a handoff process from the mobile station 3 side (Mobile Assisted Hand Off). : MAHO), or a method of giving an instruction to enter a handoff state from the base station 2 side, and is connected to the first base station 2a and the second base station 2b. The process of transition from the normal state to the handoff state may be any method. Also,
In this mobile communication system 1, the process of shifting from the handoff state to the normal state may be performed by any method.
【００２１】つぎに、上述した図１に示したように、移
動局が第１の領域４、重複領域６、第２の領域５に移動
するときにおいて、信号の種類に応じて異なるハンドオ
フ処理を行うときの一例について説明する。なお、以下
の説明においては、情報信号及び制御信号として特に送
信電力制御信号についてのハンドオフ処理について説明
する。Next, as shown in FIG. 1 described above, when the mobile station moves to the first area 4, the overlapping area 6, and the second area 5, different handoff processing is performed according to the type of signal. An example of the case will be described. In the following description, a handoff process for a transmission power control signal, particularly as an information signal and a control signal, will be described.
【００２２】移動局３は、図１（ａ）に示すように、第
１の領域４に位置するとき、第１の基地局２ａからの下
りリンク制御信号として送信電力制御信号を受信する。
移動局３は、この送信電力制御信号及び情報信号を復調
する。移動局３は、復調して得られた送信電力制御信号
に基づいて第１の基地局２ａに上りリンク信号を送信す
るときの送信電力を制御する。When the mobile station 3 is located in the first area 4 as shown in FIG. 1A, it receives a transmission power control signal as a downlink control signal from the first base station 2a.
The mobile station 3 demodulates the transmission power control signal and the information signal. The mobile station 3 controls transmission power when transmitting an uplink signal to the first base station 2a based on a transmission power control signal obtained by demodulation.
【００２３】また、この移動局３は、図１（ｂ）に示す
ように、重複領域６に位置するときにおいて、ハンドオ
フ状態とされ、第１の基地局２ａと第２の基地局２ｂと
の双方からほぼ同じ内容の下りリンク信号が送信され
る。このとき、移動局３には、第１の基地局２ａから送
信電力制御信号及び情報信号の双方が送信されるととも
に第２の基地局２ｂから送信電力制御信号のみが送信さ
れる。すなわち、移動局は、重複領域においては、送信
電力制御信号について第１の基地局２ａ及び第２の基地
局２ｂと接続されたソフトハンドオフ状態とされる。そ
して、移動局３は、第１の基地局２ａから送信された送
信電力制御信号及び情報信号と、第２の基地局２ｂから
送信された制御信号とをそれぞれ別個に受信するととも
に復調する。また、この移動局３は、第１の基地局２ａ
から送信される送信電力制御信号と第２の基地局２ｂか
ら送信される送信電力制御信号とを受信したとき、第１
の基地局２ａからの送信電力制御信号と第２の基地局２
ｂからの送信電力制御信号との内容を比較し、比較した
結果に基づいて動作を決定する。この移動局３は、送信
電力制御信号に関しては、第１の基地局２ａからの制御
信号と第２の基地局２ｂからの送信電力制御信号とを組
み合わせた結果に応じて動作を決定する。When the mobile station 3 is located in the overlapping area 6, as shown in FIG. 1B, the mobile station 3 is in a hand-off state, and the mobile station 3 is in a handoff state between the first base station 2a and the second base station 2b. Both sides transmit downlink signals having substantially the same contents. At this time, both the transmission power control signal and the information signal are transmitted from the first base station 2a to the mobile station 3, and only the transmission power control signal is transmitted from the second base station 2b. That is, the mobile station is in a soft handoff state in which the transmission power control signal is connected to the first base station 2a and the second base station 2b in the overlapping area. Then, the mobile station 3 separately receives and demodulates the transmission power control signal and the information signal transmitted from the first base station 2a and the control signal transmitted from the second base station 2b, respectively. The mobile station 3 is connected to the first base station 2a
When receiving the transmission power control signal transmitted from the second base station 2b and the transmission power control signal transmitted from the second base station 2b,
Transmission power control signal from the base station 2a and the second base station 2
b) to compare the contents with the transmission power control signal, and determine the operation based on the comparison result. The mobile station 3 determines the operation according to the result of combining the control signal from the first base station 2a and the transmission power control signal from the second base station 2b with respect to the transmission power control signal.
【００２４】具体的には、移動局３は、通常、第１の基
地局２ａと第２の基地局２ｂとの双方から送信された送
信電力制御信号が「ｕｐ」を示す信号であった場合にの
み上りリンク信号の送信電力を増加させ、それ以外の組
み合わせの場合には送信電力を無変更若しくは減少させ
て第１の基地局２ａ又は第２の基地局２ｂへの上りリン
ク信号の送信電力を制御する。なお、この他の組み合わ
せや複数の基地局及び移動局３が存在するときの組み合
わせ等で移動局３に送信電力制御信号が送信されたとき
には、Qualcomm社のIS-95に準拠した方式で送信電力を
制御しても良い。Specifically, the mobile station 3 normally operates when the transmission power control signal transmitted from both the first base station 2a and the second base station 2b is a signal indicating "up". The transmission power of the uplink signal to the first base station 2a or the second base station 2b is increased by changing the transmission power of the uplink signal to only the first base station 2a or the second base station 2b. Control. When the transmission power control signal is transmitted to the mobile station 3 in another combination or a combination in which a plurality of base stations and the mobile station 3 are present, the transmission power is controlled by a method based on Qualcomm's IS-95. May be controlled.
【００２５】なお、移動局３は、送信電力制御信号以外
を示す制御信号に関しては、第１の基地局２ａと第２の
基地局２ｂとから送信された制御信号を復調した結果、
受信電力の大きい方を採用する。また、移動局３は、送
信された下りリンク信号が誤り訂正符号化されていると
きには、当該下りリンク信号の振幅値を単純に加算して
軟判定の複合器に入力すればよい。このように動作する
ことで、移動局３は、制御信号の誤り率を低減させるこ
とができ、第１の基地局２ａ又は第２の基地局２ｂから
の命令に対する追従性を向上させることができる。The mobile station 3 demodulates control signals transmitted from the first base station 2a and the second base station 2b with respect to control signals other than the transmission power control signal.
Use the one with the higher received power. Further, when the transmitted downlink signal is error-correction coded, the mobile station 3 may simply add the amplitude value of the downlink signal and input the result to the soft-decision multiplexer. By operating in this manner, the mobile station 3 can reduce the error rate of the control signal, and can improve the ability to follow commands from the first base station 2a or the second base station 2b. .
【００２６】移動局３は、図１（ｃ）に示すように、重
複領域６から第２の領域５に移動したときには、重複領
域６でのハンドオフ状態から通常状態に戻る。このと
き、移動局３には、第２の基地局２ｂから送信電力制御
信号及び情報信号を含む下りリンク信号が送信される。
そして、移動局３は、上述した第１の領域４に位置する
ときと同様に、下りリンク信号を受信及び復調すること
により、送信電力制御信号に基づいて第２の基地局２ｂ
に上りリンク信号を送信するときの送信電力を制御す
る。When the mobile station 3 moves from the overlapping area 6 to the second area 5 as shown in FIG. 1C, the mobile station 3 returns from the handoff state in the overlapping area 6 to the normal state. At this time, a downlink signal including a transmission power control signal and an information signal is transmitted to the mobile station 3 from the second base station 2b.
Then, the mobile station 3 receives and demodulates the downlink signal in the same manner as when the mobile station 3 is located in the first area 4 described above, so that the second base station 2b based on the transmission power control signal
To control the transmission power when transmitting an uplink signal.
【００２７】上述したように、この移動体通信システム
１は、重複領域６に移動局３が位置し、当該移動局３を
ハンドオフ状態とするとき、送信電力制御信号を第１の
基地局２ａ及び第２の基地局２ｂの双方から移動局３に
送信する。そして、移動局３は、双方の基地局２からの
制御信号を組み合わせて制御するソフトハンドオフ状態
とされる。一方、移動局３は、音声情報等の情報信号に
ついては、いずれか一方の基地局からの情報信号しか受
信しないハードハンドオフ状態とされる。As described above, in the mobile communication system 1, when the mobile station 3 is located in the overlap area 6 and the mobile station 3 is in the handoff state, the mobile station 3 transmits the transmission power control signal to the first base station 2a and the base station 2a. The data is transmitted to the mobile station 3 from both of the second base stations 2b. Then, the mobile station 3 enters a soft handoff state in which control is performed by combining control signals from both base stations 2. On the other hand, the mobile station 3 is placed in a hard handoff state in which information signals such as voice information are received only from one of the base stations.
【００２８】このように、移動体通信システム１によれ
ば、移動局３をハンドオフ状態としているときに、いず
れか一方の基地局２からの情報信号を移動局３に送信
し、かつ送信電力制御命令を両方の基地局２から送信す
るようなソフトハンドオフ状態とするので、双方の基地
局２から情報信号と送信電力制御命令とを別個に移動局
３に送信することでソフトハンドオフ状態とする方式と
比較して、移動局３に向けて複数の基地局２から情報信
号を送信することにより、システムに含まれる他の移動
局３に与える干渉を低減することができる。また、この
移動体通信システム１によれば、ハンドオフ状態として
いるときに、複数の基地局から移動局３に制御信号を送
信するので、重複領域６についてはハードハンドオフを
行う方式と比較して、制御信号についての信頼度を向上
させることができる。特に、送信電力制御信号について
は、移動局３をソフトハンドオフ状態としているので、
上述の第２の基地局２ｂから移動局３の送信電力を制御
することも可能であり、移動局３から第２の基地局２ｂ
が予期できない送信電力で上りリンク信号を送信するこ
とを回避できる。As described above, according to the mobile communication system 1, when the mobile station 3 is in the handoff state, the information signal from one of the base stations 2 is transmitted to the mobile station 3, and the transmission power control is performed. Since a command is transmitted from both base stations 2 in a soft handoff state, the information signal and the transmission power control command are transmitted separately from both base stations 2 to mobile station 3 to establish a soft handoff state. By transmitting information signals from the plurality of base stations 2 to the mobile station 3 as compared with the mobile station 3, interference with other mobile stations 3 included in the system can be reduced. According to the mobile communication system 1, a control signal is transmitted from a plurality of base stations to the mobile station 3 in the handoff state, so that the overlap area 6 is compared with a method of performing a hard handoff. The reliability of the control signal can be improved. In particular, regarding the transmission power control signal, since the mobile station 3 is in the soft handoff state,
It is also possible to control the transmission power of the mobile station 3 from the above-mentioned second base station 2b.
Can avoid transmitting an uplink signal with unexpected transmission power.
【００２９】さらに、移動体通信システム１によれば、
重複領域６に移動局３が位置したとき、制御信号につい
てはソフトハンドオフ状態とし、情報信号についてはハ
ードハンドオフ状態とするので、システム全体での通信
容量を向上させることができる。例えば、移動体通信シ
ステム１において第２の基地局２ｂの通信容量がいっぱ
いであった場合にも、第２の基地局２ｂからは移動局３
に送信電力制御信号のみを送信すれば良いので、他の移
動局３に情報信号又は制御信号を送信することに対して
の影響を小さくすることができる。したがって、この移
動体通信システム１によれば、第２の基地局２ｂから送
受信する信号の干渉を抑制するとともに、第１の領域４
から第２の領域５に移動局３が移動したときに、最終的
に第１の領域４で使用していた周波数チャンネルとは異
なる周波数チャンネルを使用して第２の基地局２ｂと移
動局３との間で情報信号を送受信するようにハードハン
ドオフすることができる。Further, according to the mobile communication system 1,
When the mobile station 3 is located in the overlapping area 6, the control signal is in the soft handoff state and the information signal is in the hard handoff state, so that the communication capacity of the entire system can be improved. For example, even when the communication capacity of the second base station 2b is full in the mobile communication system 1, the mobile station 3 can be transmitted from the second base station 2b.
Since only the transmission power control signal needs to be transmitted to the other mobile station 3, the influence on transmitting the information signal or the control signal to another mobile station 3 can be reduced. Therefore, according to the mobile communication system 1, interference of signals transmitted and received from the second base station 2b is suppressed and the first area 4
When the mobile station 3 moves from the second area 5 to the second area 5, the second base station 2 b and the mobile station 3 finally use a frequency channel different from the frequency channel used in the first area 4. A hard handoff can be performed to send and receive information signals to and from the terminal.
【００３０】つぎに、上述の第１の基地局２ａ及び第２
の基地局２ｂが下記表１に示す閾値を保有しているとき
の一例について説明する。Next, the first base station 2a and the second base station 2a
An example when the base station 2b of this example has the threshold values shown in Table 1 below will be described.
【００３１】[0031]
【表１】 [Table 1]
【００３２】この表１は、例えば第１の基地局２ａ及び
第２の基地局２ｂに内蔵されているメモリに格納されて
おり、例えばＣＰＵによって読み込まれることで閾値に
応じた処理を行う。この表１は、移動局３の接続数を閾
値Ｎthとして保有しているとき、上述の重複領域６に位
置している移動局３に対する第１の基地局２ａ又は第２
の基地局２ｂのハンドオフ処理の一例を示している。Table 1 is stored in a memory built in the first base station 2a and the second base station 2b, for example, and is read by the CPU, for example, to perform a process according to the threshold. Table 1 shows that when the number of mobile stations 3 connected is held as the threshold Nth, the first base station 2a or the second base station 2a or the second
2 shows an example of a handoff process of the base station 2b.
【００３３】この表１によれば、第２の基地局２ｂの接
続数がピーク値Ｎfullに達しているときには、第１の基
地局２ａとの重複領域６に位置する移動局３を送信電力
制御信号についてのみソフトハンドオフ状態とする。一
方、情報信号については、第１の基地局２ａとは異なる
周波数チャンネルを用いてハードハンドオフを行う。According to Table 1, when the number of connections of the second base station 2b has reached the peak value Nfull, the mobile station 3 located in the overlapping area 6 with the first base station 2a is subjected to transmission power control. Only signals are in soft handoff state. On the other hand, for information signals, hard handoff is performed using a frequency channel different from that of the first base station 2a.
【００３４】第２の基地局２ｂの接続数がピーク値Ｎfu
ll〜閾値Ｎthであるときには、第１の基地局２ａとの重
複領域６に位置する移動局３を送信電力制御信号につい
てのみソフトハンドオフ状態とする。一方、第２の基地
局２ｂは、情報信号を移動局３には送信しない。The number of connections of the second base station 2b is equal to the peak value Nfu.
When ll to the threshold value Nth, the mobile station 3 located in the overlapping area 6 with the first base station 2a is set in the soft handoff state only for the transmission power control signal. On the other hand, the second base station 2 b does not transmit the information signal to the mobile station 3.
【００３５】第２の基地局２ｂの接続数が閾値Ｎth以下
であって、第２の基地局２ｂの通信容量に空きがあると
きには、重複領域６に位置する移動局３を送信電力制御
信号及び情報信号の双方についてソフトハンドオフ状態
とする。When the number of connections of the second base station 2b is less than or equal to the threshold value Nth and there is free space in the communication capacity of the second base station 2b, the mobile station 3 located in the overlapping area 6 transmits the transmission power control signal and A soft handoff state is set for both information signals.
【００３６】このような閾値Ｎthを上述の第１の基地局
２ａと第２の基地局２ｂとが保有している場合であっ
て、ある移動局３が第１の領域４から第２の領域５に移
動するときの第１の基地局２ａ及び第２の基地局２ｂの
動作について説明する。In the case where the above-mentioned first base station 2a and second base station 2b hold such a threshold value Nth, a certain mobile station 3 moves from the first area 4 to the second area. The operation of the first base station 2a and the second base station 2b when moving to No. 5 will be described.
【００３７】先ず、移動局３が第１の領域４に位置する
ときには、図３（ａ）に示すように、第１の移動局３か
らのみ制御信号及び情報信号が移動局３に対して送信さ
れる。First, when the mobile station 3 is located in the first area 4, a control signal and an information signal are transmitted to the mobile station 3 only from the first mobile station 3, as shown in FIG. Is done.
【００３８】そして、移動局３が第２の基地局２ｂに向
かって移動し、重複領域６に位置しているとき、第２の
基地局２ｂは、上述の表１に示した閾値Ｎthに応じたハ
ンドオフ処理を行う。すなわち、この第２の基地局２ｂ
は、第２の領域５における移動局３の接続数が閾値Ｎth
以上であった場合には、図３（ｂ）に示すように、制御
信号についてソフトハンドオフ状態とし、情報信号につ
いては片方の基地局２からのみ信号が送信されるハード
ハンドオフ状態とする。特に、制御信号については、送
信電力制御信号についてソフトハンドオフ状態すること
が望ましい。When the mobile station 3 moves toward the second base station 2b and is located in the overlapping area 6, the second base station 2b responds to the threshold Nth shown in Table 1 above. Performed handoff processing. That is, the second base station 2b
Is that the number of mobile stations 3 connected in the second area 5 is equal to the threshold Nth
In the case described above, as shown in FIG. 3B, the control signal is in a soft handoff state, and the information signal is in a hard handoff state in which a signal is transmitted from only one base station 2. In particular, for the control signal, it is desirable that the transmission power control signal be in a soft handoff state.
【００３９】また、この第２の基地局２ｂは、第２の領
域５における移動局３の接続数が閾値Ｎth以下であった
場合には、図３（ｃ）に示すように、制御信号及び情報
信号を移動局３に送信し、制御信号及び情報信号につい
てソフトハンドオフ状態とする。ここで、第２の基地局
２ｂの移動局３の接続数が閾値Ｎth以上となったときに
は、上述の閾値Ｎth以上となった場合に戻る。一方、第
２の基地局２ｂの移動局３の接続数が閾値Ｎth以下のま
ま移動局３が重複領域６から第２の領域５に移動したと
きには、第２の基地局２ｂから制御信号及び情報信号が
送信される。When the number of mobile stations 3 connected in the second area 5 is equal to or smaller than the threshold Nth, the second base station 2b, as shown in FIG. An information signal is transmitted to the mobile station 3, and the control signal and the information signal are set in a soft handoff state. Here, when the number of connections of the mobile station 3 of the second base station 2b becomes equal to or larger than the threshold value Nth, the process returns to the case where the connection number becomes equal to or larger than the threshold value Nth. On the other hand, when the mobile station 3 moves from the overlapping area 6 to the second area 5 while the number of connections of the mobile station 3 to the second base station 2b is equal to or less than the threshold Nth, the control signal and information from the second base station 2b are transmitted. A signal is transmitted.
【００４０】そして、移動局３が重複領域６から第２の
領域５に移動したときには、図３（ｄ）に示すように、
第２の基地局２ｂから移動局３に制御信号及び情報信号
が送信されることとなる。When the mobile station 3 moves from the overlapping area 6 to the second area 5, as shown in FIG.
The control signal and the information signal are transmitted from the second base station 2b to the mobile station 3.
【００４１】このように、この移動体通信システム１に
よれば、各基地局の通信容量に空きがあるときには、制
御信号のみならず情報信号についてもソフトハンドオフ
処理を行うことができるので、通信品質を向上させるこ
とができる。As described above, according to the mobile communication system 1, when the communication capacity of each base station is available, the soft handoff process can be performed not only for the control signal but also for the information signal, so that the communication quality can be improved. Can be improved.
【００４２】なお、この移動体通信システム１は、閾値
Ｎthが一種類の場合に、情報信号についてソフトハンド
オフ処理とハードハンドオフ処理とを繰り返すこととな
る場合が生ずるが、例えばヒステリシスを設けて急激に
ソフトハンドオフ処理とハードハンドオフ処理とを繰り
返さないように制御すればよい。In the mobile communication system 1, when the threshold value Nth is one type, the soft handoff process and the hard handoff process may be repeated with respect to the information signal. Control may be performed so that the soft handoff process and the hard handoff process are not repeated.
【００４３】つぎに、上述の第１の基地局２ａ及び第２
の基地局２ｂが下記表２に示す閾値を保有しているとき
の一例について説明する。Next, the first base station 2a and the second base station 2a
An example when the base station 2b has the threshold value shown in Table 2 below will be described.
【００４４】[0044]
【表２】 [Table 2]
【００４５】この表２は、上述と同様に、例えば第１の
基地局２ａ及び第２の基地局２ｂに内蔵されているメモ
リに格納されており、例えばＣＰＵによって読み込まれ
ることで閾値に応じた処理を行う。この表２は、通信品
質ついての閾値Ｑthとして保有しているとき、上述の重
複領域６に位置している移動局３に対する基地局のハン
ドオフ処理の一例を示している。ここで、通信品質は、
ある移動局３に対してハンドオフ処理を行っている基地
局２が行っている通信全体での通信品質である。Table 2 is stored in, for example, a memory built in the first base station 2a and the second base station 2b, as described above. Perform processing. Table 2 shows an example of a base station handoff process for the mobile station 3 located in the above-described overlapping area 6 when the threshold is held as the communication quality threshold Qth. Here, the communication quality is
This is the communication quality of the entire communication performed by the base station 2 that is performing the handoff process for a certain mobile station 3.
【００４６】この表２によれば、ある基地局２ｂが通信
品質を最悪Ｑworstと判断したときには、他の基地局と
の重複領域６に位置する移動局３を送信電力制御信号に
ついてのみソフトハンドオフ状態とする。情報信号につ
いて元いた基地局２ａで使用されていた周波数とは異な
る周波数チャンネルを用いてハードハンドオフを行う。According to Table 2, when a certain base station 2b determines that the communication quality is the worst Qworst, the mobile station 3 located in the overlapping area 6 with the other base station is placed in the soft handoff state only for the transmission power control signal. And Hard handoff is performed using a frequency channel different from the frequency used by the base station 2a for the information signal.
【００４７】基地局２ｂが通信品質を最悪Ｑworst〜閾
値Ｑthと判断したときには、他の基地局２ａとの重複領
域６に位置する移動局３を送信電力制御信号についての
みソフトハンドオフ状態とする。一方、基地局２ｂは、
情報信号を移動局３には送信しない。When the base station 2b determines that the communication quality is between the worst Qworst and the threshold Qth, the mobile station 3 located in the overlapping area 6 with the other base station 2a is placed in the soft handoff state only for the transmission power control signal. On the other hand, the base station 2b
No information signal is transmitted to the mobile station 3.
【００４８】基地局２ｂが通信品質を閾値Ｎth以下と判
断したときには、重複領域６に位置する移動局３を送信
電力制御信号及び情報信号の双方についてソフトハンド
オフ状態とする。When the base station 2b determines that the communication quality is equal to or lower than the threshold value Nth, the mobile station 3 located in the overlapping area 6 is set in a soft handoff state for both the transmission power control signal and the information signal.
【００４９】このように、移動体通信システム１は、通
信品質について閾値Ｑthを保有することにより、システ
ム全体としての特性、すなわち、システムの安定度及び
通信品質を向上させることができる。なお、この移動体
通信システム１は、ハンドオフ処理行う基地局２全体の
通信品質について閾値Ｑthを有するともに、各基地局２
で送受信する信号のＳ／Ｎ等の通信品質についての閾値
を有していても良い。As described above, the mobile communication system 1 can improve the characteristics of the entire system, that is, the stability and communication quality of the system, by retaining the threshold value Qth for the communication quality. The mobile communication system 1 has a threshold value Qth for the communication quality of the entire base station 2 that performs the handoff process, and
May have a threshold for communication quality such as S / N of a signal transmitted and received.
【００５０】さらに、この移動体通信システム１は、移
動局３の接続数又は通信品質について閾値を基地局２に
保有し、システムの通信容量がいっぱいであったとき
も、各移動局３に少なくとも送信電力制御信号を送信す
ることができるので、ハンドオフ先の基地局２ｂが送信
電力制御信号を送信することができ、移動局３からの予
期しない送信電力の信号を基地局２ｂが受信するような
ことがない。すなわち、この移動体通信システム１によ
れば、例えば移動局３が第１の領域４から第２の領域５
に移動したとき、第２の基地局２ｂは、通信容量がいっ
ぱいであっても、移動局３が重複領域６に位置するとき
に移動局３に対して送信電力制御信号を送信することが
でき、移動局３からの送信電力のレベルが大きすぎて基
地局２ｂの行っている通信信号に対して大きな干渉を与
えることなく移動局３の通信を最適化することができる
とともに、移動局３が重複領域６から第２の領域５に移
動したときでも、適当な送信電力で移動局３からの情報
信号を受信することができる。Further, the mobile communication system 1 holds a threshold value for the number of connections or the communication quality of the mobile station 3 in the base station 2, and when the communication capacity of the system is full, at least each mobile station 3 Since the transmission power control signal can be transmitted, the base station 2b at the handoff destination can transmit the transmission power control signal, and the base station 2b receives an unexpected transmission power signal from the mobile station 3. Nothing. That is, according to the mobile communication system 1, for example, the mobile station 3 moves from the first area 4 to the second area 5
, The second base station 2b can transmit a transmission power control signal to the mobile station 3 when the mobile station 3 is located in the overlapping area 6 even if the communication capacity is full. Since the level of the transmission power from the mobile station 3 is too high, the communication of the mobile station 3 can be optimized without giving a large interference to the communication signal being transmitted by the base station 2b. Even when moving from the overlapping area 6 to the second area 5, an information signal from the mobile station 3 can be received with an appropriate transmission power.
【００５１】また、上述の移動体通信システム１では、
重複領域６に位置する移動局３に対して図４（ａ）に示
すように制御信号のみを送信することで、ハンドオフ処
理を行っていたが、図４（ｂ）に示すように制御信号及
び情報信号の双方を移動局３に送信する場合と比較し
て、図４（ｃ）に示すように移動局３に送信する制御信
号の送信電力を大きくしてもよい。特に、この移動体通
信システム１は、制御信号のうち、送信電力制御信号の
送信電力を大きくすることが望ましい。In the mobile communication system 1 described above,
The handoff process was performed by transmitting only the control signal to the mobile station 3 located in the overlap area 6 as shown in FIG. 4A, but the control signal and the control signal were transmitted as shown in FIG. As shown in FIG. 4C, the transmission power of the control signal transmitted to the mobile station 3 may be increased as compared with the case where both information signals are transmitted to the mobile station 3. In particular, in the mobile communication system 1, it is desirable to increase the transmission power of the transmission power control signal among the control signals.
【００５２】このように、移動体通信システム１は、制
御信号についてのみ移動局３をソフトハンドオフ状態と
するとき、送信電力制御信号等の制御信号の送信波電力
を増加させることにより、移動局３における送信電力制
御信号の受信誤り率を低減することができる。したがっ
て、この移動体通信システム１によれば、送信電力制御
信号の送信波電力を増加させることにより若干通信容量
が減少するものの、システム全体での安定性を向上させ
ることができる。なお、この移動体通信システム１は、
送信電力制御信号の送信波電力を増加させても、制御信
号についてのみソフトハンドオフ処理をしており、情報
信号についてはハードハンドオフ処理をしているので、
送信波電力を増加させても全体として考えれば他の信号
への干渉が抑制される。As described above, the mobile communication system 1 increases the transmission wave power of the control signal such as the transmission power control signal when the mobile station 3 is in the soft hand-off state only for the control signal. , The reception error rate of the transmission power control signal can be reduced. Therefore, according to the mobile communication system 1, although the communication capacity is slightly reduced by increasing the transmission wave power of the transmission power control signal, the stability of the entire system can be improved. This mobile communication system 1
Even if the transmission wave power of the transmission power control signal is increased, only the control signal is subjected to soft handoff processing, and the information signal is subjected to hard handoff processing.
Even if the transmission wave power is increased, interference with other signals is suppressed as a whole.
【００５３】[0053]
【発明の効果】以上詳細に説明したように、本発明に係
る移動通信システムは、ハンドオフ処理を行うときに、
少なくとも下りリンク制御信号について複数の移動局を
同時に接続するソフトハンドオフ制御を行い、下りリン
ク制御信号以外についてはハードハンドオフ制御を行う
基地局を備えているので、下りリンク制御信号及びそれ
以外の音声等を示す情報信号の双方についてソフトハン
ドオフ制御を行う基地局を備えるシステムと比較してシ
ステム全体での通信容量を増加させる。また、この移動
通信システムによれば、少なくとも下りリンク制御信号
を移動局に送信するので、システム全体の安定性を保持
できる。さらに、この移動通信システムによれば、例え
ば基地局の通信容量がいっぱいであったときにも、ハン
ドオフ先の基地局が他の通信に対して与える干渉を最低
限とすべく、下りリンク制御信号のみを移動局に対して
送信してソフトハンドオフ処理を行うので、ハンドオフ
先の基地局が予期しない送信電力の上りリンク信号を受
信するようなことがなく、システムの安全性を向上させ
ることができる。As described above in detail, the mobile communication system according to the present invention performs
At least a base station that performs soft handoff control for simultaneously connecting a plurality of mobile stations for downlink control signals and performs hard handoff control for other than downlink control signals is provided. The communication capacity of the entire system is increased as compared with a system including a base station that performs soft handoff control on both of the information signals indicating the above. Further, according to this mobile communication system, at least the downlink control signal is transmitted to the mobile station, so that the stability of the entire system can be maintained. Further, according to this mobile communication system, for example, even when the communication capacity of the base station is full, a downlink control signal is provided to minimize the interference that the base station of the handoff destination gives to other communications. Since the soft handoff process is performed by transmitting only the mobile station to the mobile station, the base station at the handoff destination does not receive an uplink signal having unexpected transmission power, thereby improving system security. .
【図１】（ａ）が第１の領域に移動局が位置するときに
第１の基地局から移動局に送信する下りリンク信号を説
明する図であり、（ｂ）が重複領域に移動局が位置する
ときに第１の基地局及び第２の基地局から移動局に送信
する下りリンク信号を説明する図であり、（ｃ）が第２
の領域に移動局が位置するときに第２の基地局から移動
局に送信する下りリンク信号を説明する図である。1A is a diagram illustrating a downlink signal transmitted from a first base station to a mobile station when the mobile station is located in a first area, and FIG. 1B is a diagram illustrating a mobile station in an overlap area. FIG. 5 is a diagram illustrating downlink signals transmitted from the first base station and the second base station to the mobile station when is located, and FIG.
FIG. 5 is a diagram illustrating a downlink signal transmitted from a second base station to a mobile station when the mobile station is located in a region of FIG.
【図２】移動局が第１の領域から重複領域、第２の領域
を移動するときの第１の基地局及び第２の基地局の受信
電力を示す図である。FIG. 2 is a diagram illustrating received powers of a first base station and a second base station when a mobile station moves from a first area to an overlapping area and to a second area.
【図３】（ａ）が第１の領域に移動局が位置するときに
第１の基地局から移動局に送信する下りリンク信号を説
明する図であり、（ｂ）が重複領域に移動局が位置する
ときに第２の基地局の移動局との接続数が閾値Ｎth以上
であるときの第１の基地局及び第２の基地局から移動局
に送信する下りリンク信号を説明する図であり、（ｃ）
が重複領域に移動局が位置するときに第２の基地局の移
動局との接続数が閾値Ｎth以下であるときの第１の基地
局及び第２の基地局から移動局に送信する下りリンク信
号を説明する図であり、（ｄ）が第２の領域に移動局が
位置するときに第２の基地局から移動局に送信する下り
リンク信号を説明する図である。3A is a diagram illustrating a downlink signal transmitted from the first base station to the mobile station when the mobile station is located in the first area, and FIG. 3B is a diagram illustrating the mobile station in the overlap area. FIG. 7 is a diagram illustrating downlink signals transmitted from the first base station and the second base station to the mobile station when the number of connections of the second base station to the mobile station is equal to or greater than a threshold Nth when is located. Yes, (c)
Is transmitted from the first base station and the second base station to the mobile station when the number of connections of the second base station to the mobile station is equal to or less than the threshold Nth when the mobile station is located in the overlap area. It is a figure explaining a signal, and (d) is a figure explaining a downlink signal transmitted to a mobile station from a 2nd base station when a mobile station is located in the 2nd field.
【図４】（ａ）が制御信号についてのみソフトハンドオ
フを行うときの第２の基地局から移動局に送信する下り
リンク信号を示す図であり、（ｂ）が従来のIS-95にお
ける第２の基地局から移動局に送信する下りリンク信号
を示す図であり、（ｃ）が制御信号についてのみソフト
ハンドオフを行うときの第２の基地局から移動局に送信
する下りリンク信号の送信電力を増加させることを説明
するための図である。4A is a diagram illustrating a downlink signal transmitted from a second base station to a mobile station when soft handoff is performed only for a control signal, and FIG. 4B is a diagram illustrating a second downlink signal in a conventional IS-95. FIG. 3C is a diagram illustrating a downlink signal transmitted from the base station to the mobile station, and FIG. 4C illustrates transmission power of a downlink signal transmitted from the second base station to the mobile station when soft handoff is performed only for a control signal. It is a figure for explaining increasing.
【図５】従来のセルラーシステムにおいてハンドオフ処
理を説明するための図である。FIG. 5 is a diagram for explaining a handoff process in a conventional cellular system.
１ 移動体通信システム、２ 基地局、２ａ 第１の基
地局、２ｂ 第２の基地局、３ 移動局、４ 第１の領
域、５ 第２の領域、６ 重複領域Reference Signs List 1 mobile communication system, 2 base stations, 2a first base station, 2b second base station, 3 mobile station, 4 first area, 5 second area, 6 overlapping area
Claims (5)
れるセル間を移動する移動局とが符号分割多元接続方式
で接続され、上記基地局により送信電力制御がなされる
移動通信システムにおいて、 少なくとも下りリンク制御信号について上記移動局と上
記各基地局とを同時に接続するソフトハンドオフ制御を
行い、上記下りリンク制御信号以外の下りリンク信号に
ついてはハードハンドオフ制御を行うことを特徴とする
移動通信システム。1. A mobile communication system in which a plurality of base stations and mobile stations moving between cells formed by the respective base stations are connected by a code division multiple access system and transmission power control is performed by the base stations. Mobile communication characterized by performing soft handoff control for simultaneously connecting the mobile station and each of the base stations for at least a downlink control signal, and performing hard handoff control for downlink signals other than the downlink control signal. system.
号として移動局の送信電力制御信号を送信し、少なくと
も送信電力制御信号についてソフトハンドオフ制御を行
うことを特徴とする請求項１記載の移動通信システム。2. The mobile station according to claim 1, wherein each of the base stations transmits a transmission power control signal of the mobile station as the downlink control signal, and performs soft handoff control on at least the transmission power control signal. Communications system.
続される接続数に関する閾値を監視する接続数監視手段
を備え、 上記接続数監視手段は、上記移動局の接続数が上記閾値
以上であるときには上記下りリンク制御信号のみについ
てソフトハンドオフ制御を行わせ、上記移動局の接続数
が上記閾値以下であるときには上記下りリンク制御信号
及び下りリンク制御信号以外の信号についてソフトハン
ドオフ制御を行わせることを特徴とする請求項１記載の
移動通信システム。3. Each of the base stations comprises a connection number monitoring means for simultaneously monitoring a threshold value relating to the number of connections to which the mobile station is connected, wherein the connection number monitoring means is such that the connection number of the mobile station is equal to or greater than the threshold value When, the soft handoff control is performed only for the downlink control signal, and when the number of mobile stations connected is equal to or less than the threshold, the soft handoff control is performed for signals other than the downlink control signal and the downlink control signal. The mobile communication system according to claim 1, wherein:
信号品質に関する閾値を監視する品質監視手段を備え、 上記品質監視手段は、上記信号品質が上記閾値以上であ
るときには上記下りリンク制御信号のみについてソフト
ハンドオフ制御を行わせ、上記信号品質が上記閾値以下
であるときには上記下りリンク制御信号及び下りリンク
制御信号以外の下りリンク信号についてソフトハンドオ
フ制御を行わせることを特徴とする請求項１記載の移動
通信システム。4. Each of the base stations includes quality monitoring means for monitoring a threshold value regarding signal quality between the mobile stations, wherein the quality monitoring means is configured to transmit the downlink control signal when the signal quality is equal to or higher than the threshold value. 2. A soft handoff control is performed for only the downlink control signal and a soft handoff control is performed on a downlink signal other than the downlink control signal when the signal quality is equal to or less than the threshold value. Mobile communication system.
信号についてハードハンドオフ制御を行うとき、上記下
りリンク制御信号についての制御信号レベルを、上記下
りリンク制御信号以外の信号についてもソフトハンドオ
フ制御を行うときの下りリンク制御信号の制御信号レベ
ルよりも高くすることを特徴とする請求項１記載の移動
通信システム。5. The base station, when performing hard handoff control on a signal other than the downlink control signal, sets a control signal level for the downlink control signal and soft handoff control for a signal other than the downlink control signal. 2. The mobile communication system according to claim 1, wherein the control signal level is higher than a control signal level of a downlink control signal when performing.
Priority Applications (7)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP11750798A JP3956479B2 (en) | 1998-04-27 | 1998-04-27 | Mobile communication system, mobile station and base station |
| KR1019990014151A KR100600870B1 (en) | 1998-04-27 | 1999-04-21 | Mobile radio communication system |
| DE1999625952 DE69925952T2 (en) | 1998-04-27 | 1999-04-22 | Gentle handover in a mobile communication system |
| EP19990303124 EP0954194B1 (en) | 1998-04-27 | 1999-04-22 | Soft handoff in a mobile radio communication system |
| US09/296,416 US6263205B1 (en) | 1998-04-27 | 1999-04-23 | Mobile radio communication system |
| KR1020060035394A KR100600864B1 (en) | 1998-04-27 | 2006-04-19 | Mobile radio communication system |
| US13/524,238 USRE44322E1 (en) | 1998-04-27 | 2012-06-15 | Mobile radio communication system |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP11750798A JP3956479B2 (en) | 1998-04-27 | 1998-04-27 | Mobile communication system, mobile station and base station |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH11313356A true JPH11313356A (en) | 1999-11-09 |
| JP3956479B2 JP3956479B2 (en) | 2007-08-08 |
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| JP11750798A Expired - Lifetime JP3956479B2 (en) | 1998-04-27 | 1998-04-27 | Mobile communication system, mobile station and base station |
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| US (2) | US6263205B1 (en) |
| EP (1) | EP0954194B1 (en) |
| JP (1) | JP3956479B2 (en) |
| KR (2) | KR100600870B1 (en) |
| DE (1) | DE69925952T2 (en) |
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| WO2003084274A1 (en) * | 2002-04-03 | 2003-10-09 | Nec Corporation | Cellular system, base station, mobile station, and communication control method |
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| JP2014506103A (en) * | 2011-02-14 | 2014-03-06 | クゥアルコム・インコーポレイテッド | Method and apparatus for inter-cell uplink interference control |
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Also Published As
| Publication number | Publication date |
|---|---|
| KR20060038437A (en) | 2006-05-03 |
| EP0954194A3 (en) | 2000-06-07 |
| KR100600870B1 (en) | 2006-07-14 |
| US6263205B1 (en) | 2001-07-17 |
| USRE44322E1 (en) | 2013-06-25 |
| DE69925952T2 (en) | 2006-05-11 |
| JP3956479B2 (en) | 2007-08-08 |
| KR19990083359A (en) | 1999-11-25 |
| EP0954194A2 (en) | 1999-11-03 |
| EP0954194B1 (en) | 2005-06-29 |
| DE69925952D1 (en) | 2005-08-04 |
| KR100600864B1 (en) | 2006-07-18 |
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